ABC News' Alex Green Reports: Barack Obama won the presidential election on Tuesday but did the Democrats' win contribute to the passage of a measure banning gay marriage in California?It's a question being hotly debated in the blogosphere and the theory goes something like this: a popular, African-American presidential contender increases black turnout. Blacks, by in large, oppose gay marriage. Therefore, proposition eight banning gay marriage in a Democratic-leaning state such as California passes 52-48 percent.Turns out it's not quite that simple. "Whites voted very narrowly against the ban, 51-49 percent. Asian-Americans voted the same. Hispanics voted for it, by 53-47 percent. Blacks voted for it, overwhelmingly, 70-30. Blacks can be said to have put it over the top. Hypothetically, had no blacks voted, we compute a vote of 50-50," according to an analysis by ABC News Polling Director Gary Langer.Yes, black Californians who voted for Obama also supported the gay marriage ban by a wide margin but so did Hispanics. And white and Asian-American opposition to the ban wasn't large enough to overcome the spread, so to speak.That said, African-American opposition to gay marriage and gay civil unions is not new. In an ABC News/Washington Post poll in late 2007, blacks opposed gay civil unions by 58-36 percent. (Whites were in favor, 55-41.) In earlier polling we've done on gay marriage, blacks have been even more broadly opposed, 66-31 percent.Some may find irony in the idea that as Sen. Obama took a major step forward for civil rights breakthrough his candidacy helped fuel at least in part the restriction of another group's civil rights.Obama didn't take a hard line against the proposition, routinely stating that he did not support Proposition 8 but personally doesn't believe in gay marriage."I think that he [Mr. Obama] was very resolute in his statements along with Senator Biden. If anything might have added to the confusion it was how that statement was misconstrued," said Andrea Shorter, Director of And Marriage For All, a gay rights advocacy group."The support against Proposition 8 among African Americans wasn't eroding until a mailer from Yes On 8 [the campaign driving Proposition 8] had a picture of Barack Obama with a statement that he supported Yes On 8 [though he doesn't]," Shorter added.Nevertheless, to change perception of gay Americans in California's black communities, And Marriage For All will be holding next steps meetings with black clergymen and other community allies. "The type of change that Proposition 8 is attempting to do goes against the foundational legal principles in our Constitution . . . equal protection against minority groups in the Constitution," said Jennifer Pizer Senior Council for Lambda Legal, a gay rights legal advocacy group. The challenge is unique: Obama's candidacy drove historic black turnout. Proposition 8's passage can't entirely be attributed to any one single race but gay rights groups across the country are going to have to rally support among a much more politically engaged black community.